Preparation and characterization of catalytic membranes containing sulfonated polyethersulfone for biodiesel production

摘要

Membranes made from sulfonated polyethersulfone (SPES) have been widely studied as ultrafiltration membranes, pervaporation membranes and proton exchange membranes for fuel cell; while there was little attempt to investigate catalytic performance of SPES for esterification. In the present paper, the catalytic performances of SPES membrane and its blends were tested by the esterification of the acidified oil with methanol for producing biodiesel. It was found that both SPES membrane and SPES/PES blend membrane as heterogeneous catalysts showed an excellent catalytic performance for esterification. Under optimum esterification conditions, the conversion of free fatty acid in the acidified oil (acid value is 153 mgKOH/g) achieved approximately 97% for both SPES and SPES/PES catalytic membranes. The excellent catalytic performance of these membranes resulted from the dense sulfonic groups on the PES chains. And the SPES/PES blend membrane exhibited better catalytic stability compared to the SPES membrane. Catalytic stability of SPES/PES samples with different degree of sulfonation (DS) were studied and the SPES/PES sample with DS=20.3% had the highest catalytic stability.